1. Field of the Invention
The present invention relates to an interchangeable lens to be removably attached to a camera body.
2. Description of Related Art
There is a known technique that, in a camera system constituted with a camera body and an interchangeable lens, the camera body drives a focusing lens in the interchangeable lens so as to perform auto focusing. To perform the auto focusing, the camera body needs to obtain position information of the focusing lens from the interchangeable lens. Japanese Laid Open Patent Publication No. 2008-97006, for example, states a taking lens in which the drive system of the focusing lens is provided with a movement signal generator constituted with an encoder and the like. This movement signal generator outputs a two-phase pulse signal of positive and negative in accordance with back and forth movement of the focusing lens. The output pulse signal is transmitted to a body-side control section in the camera body. The camera body can detect the movement distance of the focusing lens from the pulse signal in units of the number of pulses.
Japanese Laid Open Patent Publication No. 2008-97006 states a structure in which an encoder must be added for each optical member if information on a drive status of an optical member other than the focusing lens is transmitted to the camera body. Since addition of the encoder results in increases in manufacturing cost and in housing size, consideration is being made as to, in place of the encoder, an introduction of a new transmission path through which information on the drive status of the optical member is transmitted.